U.S. patent number 11,065,556 [Application Number 16/633,112] was granted by the patent office on 2021-07-20 for method for separating and purifying mixture having small difference in boiling points.
This patent grant is currently assigned to LG CHEM, LTD.. The grantee listed for this patent is LG CHEM, LTD.. Invention is credited to Yong Mann Beyun, Ji Hye Kim, Sung Kyun Kim, Sung Kyu Lee, Joon Ho Shin.
United States Patent |
11,065,556 |
Kim , et al. |
July 20, 2021 |
Method for separating and purifying mixture having small difference
in boiling points
Abstract
Provided is a method of separating and purifying a mixture of
components having small difference in boiling point, and the method
may maximize an energy collecting amount and collect a product to
be desired in high purity and high yield.
Inventors: |
Kim; Sung Kyun (Daejeon,
KR), Lee; Sung Kyu (Daejeon, KR), Kim; Ji
Hye (Daejeon, KR), Beyun; Yong Mann (Daejeon,
KR), Shin; Joon Ho (Daejeon, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG CHEM, LTD. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG CHEM, LTD. (Seoul,
KR)
|
Family
ID: |
1000005688640 |
Appl.
No.: |
16/633,112 |
Filed: |
August 17, 2018 |
PCT
Filed: |
August 17, 2018 |
PCT No.: |
PCT/KR2018/009456 |
371(c)(1),(2),(4) Date: |
January 22, 2020 |
PCT
Pub. No.: |
WO2019/039798 |
PCT
Pub. Date: |
February 28, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200230518 A1 |
Jul 23, 2020 |
|
Foreign Application Priority Data
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|
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Aug 25, 2017 [KR] |
|
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10-2017-0108105 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D
3/143 (20130101); B01D 3/32 (20130101); B01D
3/007 (20130101); B01D 3/4294 (20130101); B01D
3/4205 (20130101); B01D 3/4222 (20130101) |
Current International
Class: |
B01D
3/14 (20060101); B01D 3/32 (20060101); B01D
3/42 (20060101); B01D 3/00 (20060101) |
References Cited
[Referenced By]
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105142747 |
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105229119 |
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CN |
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105658291 |
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Jun 2016 |
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CN |
|
106699565 |
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May 2017 |
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CN |
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1109607 |
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EP |
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3195915 |
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10-2014-0092783 |
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10-1550150 |
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KR |
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Dec 1999 |
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WO |
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Other References
ESPACENET translation of CN 106699565 A Obtained Feb. 9, 2021.
(Year: 2021). cited by examiner .
You, et al., "Low Pressure Design for Reducing Energy Cost of
Extractive Distillation for Separating Dilsopropyl Ether and
Isopropyl Alcohol", Chemical Engineering Research and Design,
Elsevier, 2016, 109, pp. 540-552. (10.1016/j.cherd.2016.01.026.
hal-01340000). cited by applicant.
|
Primary Examiner: Miller; Jonathan
Attorney, Agent or Firm: Dentons US LLP
Claims
The invention claimed is:
1. A method of purifying a mixture, the method comprising: feeding
a mixture of three or more components to a first distillation
column, each of the three or more components having different
boiling points; obtaining a lower fraction from a lower portion of
the first distillation column, the lower fraction of the first
distillation column comprising heavy components, and obtaining an
upper fraction from an upper portion of the first distillation
column, the upper fraction of the first distillation column
comprising light components and a product to be collected; feeding
the upper fraction of the first distillation column to a second
distillation column, collecting a first lower fraction from a lower
portion of the second distillation column, the first lower fraction
of the second distillation column comprising the product; and
collecting an upper fraction from an upper portion of the second
distillation column, the upper fraction of the second distillation
column comprising lights components, wherein heat possessed by the
upper fraction of the first distillation column is fed to the lower
portion of the second distillation column through a first heat
exchanger, such that the heat is fed to a second lower fraction
collected from the lower portion of the second distillation column,
subsequently, feeding a part of the upper fraction of the first
distillation column to the second distillation column as a feed
stream, and refluxing a remaining part of the upper fraction of the
first distillation column to the upper portion of the first
distillation column, condensing and refluxing a part of the light
components collected from the upper portion of the second
distillation column to the second distillation column, and
controlling a ratio K of an upper reflux R2 of the second
distillation column and an upper reflux R1 of the first
distillation column (R2/R1) to be from 1.05 to 1.5.
2. The method of purifying a mixture of claim 1, wherein the
difference between the boiling point of each of the three or more
components of the mixture is 15.degree. C. or less.
3. The method of purifying a mixture of claim 1, wherein an
operating pressure of the first distillation column is higher than
an operating pressure of the second distillation column by 3.5
kgf/cm.sup.2 or more.
4. The method of purifying a mixture of claim 1, wherein the second
lower fraction of the second distillation column to which the heat
is fed from the first heat exchanger is returned to the second
distillation column.
5. The method of purifying a mixture of claim 1, wherein a part of
the first lower fraction of the second distillation column is
reheated and then returned to the second distillation column.
6. The method of purifying a mixture of claim 1, wherein the upper
fraction of the first distillation column is fed to the first heat
exchanger, and a separate condenser is not provided in the upper
portion of the first distillation column.
7. The method of purifying a mixture of claim 1, wherein the heavy
components collected from the lower portion of the first
distillation column are reheated, and then a part of the heavy
components are used in preheating of the mixture fed to the first
distillation column through a second heat exchanger and then
collected.
8. The method of purifying a mixture of claim 7, wherein a
remaining part of the heavy components which are collected from the
lower portion of the first distillation column and then reheated is
returned to the first distillation column.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the U.S. national stage of international
application No. PCT/KR2018/009456, filed on Aug. 17, 2018, and
claims the benefit of priority to Korean Patent Application No.
10-2017-0108105, filed on Aug. 25, 2017, the disclosures of which
are incorporated as a part herein in their entirety.
TECHNICAL FIELD
The present invention relates to a method of separating and
purifying a mixture of three or more components having small
difference in boiling point.
BACKGROUND ART
In a chemical process, a mixture of three or more components should
be often separated and purified. In this case, a distillation
process by difference in boiling point is often used in most of the
separation and purification processes. However, when the difference
in boiling point of the components is small, it is difficult to
efficiently proceed with the separation and purification
process.
FIG. 1 schematically illustrates a general ternary separation and
purification process. In a first distillation column (a heavy end
cut column), heavy components are separated in a lower portion, and
a product to be collected and light components are collected in an
upper portion. The collected product and the light components are
sent again to a second distillation column (a light end cut
column), and the light components are separated in the upper
portion and the product is produced in the lower portion.
However, when the difference in boiling point between the main
components of the light components and the heavy components is
within 15.degree. C., distillation column separation becomes
difficult, and additional process energy is taken thereon and
operation stability is inhibited.
Accordingly, there is a need to develop a process to allow a
desired product to be collected in high yield with less energy from
a multi-component mixture having small difference in boiling
point.
DISCLOSURE
Technical Problem
The present invention is directed to providing an energy saving
process which may efficiently separate and purify a mixture
including three or more components having small difference in
boiling point, and secure operation stability.
Technical Solution
In one aspect, a method of purifying a mixture includes:
feeding a mixture of three or more components having different
boiling points from each other to a first distillation column to
obtain heavy components from a lower portion of the first
distillation column, and obtain an upper fraction including light
components and a product to be collected from an upper portion of
the first distillation column; and
feeding the upper fraction to a second distillation column to
collect a first lower fraction rich in the product from a lower
portion of the second distillation column, and collect the light
components from an upper portion of the second distillation
column,
wherein heat possessed by the upper fraction collected from the
upper portion of the first distillation column is fed to the lower
portion of the second distillation column through a first heat
exchanger,
after the upper fraction of the first distillation column feeds the
heat to a second lower fraction collected from the lower portion of
the second distillation column in the first heat exchanger, a part
of the upper fraction of the first distillation column is fed to
the second distillation column as a feed stream, and the rest of
the upper fraction of the first distillation column is refluxed
(R1) to the upper portion of the first distillation column,
a part of the light components collected from the upper portion of
the second distillation column C2 is condensed and refluxed (R2) to
the second distillation column C2, and
when a ratio of an upper reflux R2 of the second distillation
column and an upper reflux R1 of the first distillation column
(R2/R1) is K, K is 1.05 or more and 1.5 or less.
According to an exemplary embodiment, the difference in boiling
point of each component included in the mixture of three or more
components having different boiling points from each other may be
within 15.degree. C.
Operation pressure of the first distillation column may be higher
than operation pressure of the second distillation column by 3.5
kgf/cm.sup.2 or more.
According to an exemplary embodiment, the second lower fraction of
the second distillation column to which the heat is fed from the
first heat exchanger may be refluxed to the second distillation
column.
According to an exemplary embodiment, a part of the first lower
fraction of the second distillation column may be reheated and then
refluxed.
According to an exemplary embodiment, all of the upper fraction of
the first distillation column may be fed to the first heat
exchanger, and a separate condenser may not be provided in the
upper portion of the first distillation column.
According to an exemplary embodiment, the heavy components
collected from the lower portion of the first distillation column
may be reheated, and then, may be used in preheating of the mixture
fed to the first distillation column through a second heat
exchanger and collected.
According to an exemplary embodiment, a part of the heavy
components which are collected from the lower portion of the first
distillation column and then reheated may be refluxed.
Advantageous Effects
According to the present invention, in a process of separating and
purifying a mixture of multi-components having small difference in
boiling point, energy saving and operation stability may be
secured, while purification efficiency may be maximized.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 schematically illustrates a general separation and
purification process of a ternary mixture.
FIG. 2 schematically illustrates a process according to an
exemplary embodiment of the present invention.
FIG. 3 is a graph showing total energy depending on a reflux
ratio.
FIG. 4 is a heat exchange amount depending on a reflux ratio.
FIG. 5 is a composition depending on a reflux ratio.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the method according to the present invention will be
described referring to FIGS. 2 to 5, and since the drawings are
only an exemplary embodiment of the present invention, they should
not be regarded as limiting the protection scope of the invention
which is apparent from the claims and the entire specification.
The present invention relates to a method of separating and
purifying a mixture including three or more components having
difference in boiling point within 15.degree. C., or within
10.degree. C.
The present invention may be also used in a method of separating
and purifying 1-butene more economically in high purity and high
yield from a raffinate-2 stream discharged from a separation
process of a C4 mixture. However, the present invention is not
limited to this use, and may be efficiently utilized in a
separation and purification process of a multi-component mixture
having small difference in boiling point.
FIG. 2 illustrates a method according to an exemplary embodiment of
the present invention.
The method of purifying a mixture according to the present
invention includes:
feeding a mixture 10 including three or more components having
small difference in boiling point to a first distillation column C1
to obtain heavy components 11 from a lower portion of the first
distillation column C1, and collect an upper fraction 12 of the
first distillation column including a product to be collected from
the upper portion; and
feeding the upper fraction 12 to a second distillation column C2 to
collect a first lower fraction 21 rich in the product to be
collected from a lower portion of the second distillation column
C2, and collect the light components 22 from an upper portion of
the second distillation column C2,
wherein heat possessed by the upper fraction 12 collected from the
upper portion of the first distillation column C1 is fed to the
lower portion of the second distillation column C2 through a first
heat exchanger E1, and
when a ratio of an upper reflux R2 of the second distillation
column and an upper reflux R1 of the first distillation column
(R2/R1) is K, K is 1.05 or more and 1.5 or less, as one
characteristic of the present invention.
That is, after the upper fraction 12 of the first distillation
column C1 feeds the heat to a second lower fraction 23 collected
from the lower portion of the second distillation column C2 in the
first heat exchanger E1, a part 12-1 of the upper fraction of the
first distillation column is fed to the second distillation column
C2 as a feed stream, and the rest 12-2 of the upper fraction of the
first distillation column is refluxed (R1) to the upper portion of
the first distillation column C1.
In addition, a part of the light components 22 collected from the
upper portion of the second distillation column C2 is condensed
with a condenser Con to be refluxed (R2) to the second distillation
column C2.
When the K value is less than the above range, a non-condensed heat
source occurs to reduce operation stability, and in a severe case,
the product may not satisfy a desired standard. In addition, when
the K value is more than the above range, a heat source required
for the second distillation column is increased more than
necessary, so that the total calories are increased more than those
of the conventional process, and thus, there may be no meaning to
utilize the heat source in the upper portion of the first
distillation column. A preferred range of the K value may be 1.05
or more and 1.5 or less, or 1.3 or less, or 1.1 or less.
Meanwhile, the operation pressure of the first distillation column
may be higher than the operation pressure of the second
distillation column by 3.5 kgf/cm.sup.2 or more. This is because it
was confirmed that a condensation temperature of the first
distillation column is advantageous for double-effect distillation
(DEC) to have enough pressure to heat the second distillation
column. A preferred range is 3.5 to 5.5 kgf/cm.sup.2, or 3.5 to 5.0
kgf/cm.sup.2, or 4.0 to 5.5 kgf/cm.sup.2, or 4.0 to 5.0
kgf/cm.sup.2.
In addition, the second lower fraction 23 of the second
distillation column C2 to which heat is fed from the first heat
exchanger E1 is refluxed to the second distillation column C2.
In addition, a part 25 of the first lower fraction 21 of the second
distillation column C2 may be reheated by a reheater b2 and then
refluxed to the second distillation column C2.
It is advantageous that the lower fraction of the second
distillation column C2 is divided into the first lower fraction 21
and the second lower fraction 23 and injected to the heat
exchanger, respectively, since the heat may be used when calories
required for the second distillation column are not fed from the
reheater b2 and start-up for an initial process.
According to an exemplary embodiment, all of the upper fraction 12
of the first distillation column C1 may be fed to the first heat
exchanger E1, and a separate condenser may not be provided in the
upper portion of the first distillation column C1. That is, the
condenser may be omitted by double-effect distillation (DEC) using
the first heat exchanger.
The heavy components 11 collected from the lower portion of the
first distillation column C1 may be reheated by the reheater b1,
and then a part 13 of the heavy components 11 are used in
preheating of the mixture 10 fed to the first distillation column
C1, through a second heat exchanger E2 and then collected.
Here, a part 15 of the heavy components which are collected from
the lower portion of the first distillation column C1 and then
reheated by the reheater b1 may be refluxed to the first
distillation column C1.
The method according to the present invention is very good in term
of having an energy saving effect of 30% or more.
EXAMPLES
Hereinafter, the Examples of the present invention will be
described.
Examples 1 to 4
A mixture having the properties shown in the following Table 1 was
subjected to 1-butene purification using the process illustrated in
FIG. 2. Process conditions and results are shown in Table 2.
TABLE-US-00001 TABLE 1 Component Mass Frac. C3's 0.48% C4 paraffin
29.18% 1-butene 43.73% Isobutene 0.25% C4 olefin 25.94% C5's 0.42%
Sum 100%
Comparative Example 1
A purification process was carried out using the process
illustrated in FIG. 1 under the conditions shown in Table 2.
Comparative Examples 2 to 4
The purification process of FIG. 2 was carried out, except that the
reflux ratio K is changed as shown in Table 2.
TABLE-US-00002 TABLE 2 Comp. Comp. Comp. Comp. Exam- Exam- Exam-
Exam- Ex. 1 Ex. 2 Ex. 3 Ex. 4 ple 1 ple 2 ple 3 ple 4 Heavy end
Upper 5.7 10.1 10.1 10.1 10.1 10.1 10.1 10.1 cut portion column
pressure (KG) Upper 51.8 73.1 73.1 73.1 73.1 73.1 73.1 73.1 portion
temperature (.degree. C.) Cond. Q (G 5.43 6.76 6.76 6.76 6.76 6.76
6.76 6.76 cal/hr) QNC (G 0.00 1.48 0.49 0.00 0.00 0.00 0.00 0.00
cal/hr) Reb. Q (G 5.42 6.90 6.90 6.90 6.90 6.90 6.90 6.90 cal/hr)
Light end Upper 6.6 6.6 6.6 6.6 6.6 6.6 6.6 6.6 cut portion column
pressure (KG) Lower 61.9 61.9 61.9 61.9 61.9 61.9 61.9 61.9 portion
temperature (.degree. C.) Product Spec. Spec. Spec. Spec. Spec.
Spec. Spec. Spec. purity (%) in Out in in in in in in Cond. Q (G
5.18 5.32 6.31 10.57 6.96 7.29 8.60 9.91 cal/hr) Reb. Q (G 5.20
5.28 6.27 10.53 6.92 7.25 8.56 9.87 cal/hr) QLP (G 5.20 0.00 0.00
17.29 13.68 14.01 15.32 16.63 cal/hr) Energy K (reflux 0.80 0.95
1.60 1.05 1.10 1.30 1.50 comparison ratio) Process 0.00 5.28 6.27
6.76 6.76 6.76 6.76 6.76 collecting calorie (G cal/hr) CW used
10.61 6.80 6.80 10.57 6.96 7.29 8.60 9.91 calorie (G cal/hr) Total
Q (G 10.62 6.90 6.90 10.66 7.06 7.38 8.70 10.01 cal/hr) Reduction
-- 35.07 35.07 -0.40 33.56 30.47 18.13 5.78 ratio (%)
From the above results, it was found that when the K value is less
than 1.05, a vapor uncondensed heat source (QNC) occurs in the
upper portion of the first distillation column to reduce operation
stability, and in a severe case, the product may not satisfy a
desired standard (Comparative Examples 2 and 3).
In addition, when the K value is more than 1.5, a heat source
required for the second distillation column is increased more than
necessary, so that the total calories are increased more than those
of the conventional process, and thus, it was found that there is
no meaning to utilize the heat source in the upper portion of the
first distillation column (Comparative Example 4).
It was confirmed from Examples 1 to 4 that when the K value is more
than 1.05, operation stability and a product standard are secured,
so that the heat source required for the second distillation column
(QLP) tends to be increased. In addition, in Examples 1 to 4, upper
portion pressure difference between the first distillation column
C1 and the second distillation column C2 is 3.5 kgf/cm.sup.2 or
more, and thus, it was found that heat exchange is possible and
energy is saved.
FIGS. 3 to 5 are graphs analyzing total energy, a heat exchange
amount, and a composition depending on the K value, respectively.
Only the reflux ratio of the second distillation column was
changed, while the operation conditions of the first distillation
column were maintained identically.
It is shown in FIGS. 3 to 5 that the feeding calories Qc are
constant, which represents that the heat source which may be fed to
the second distillation column is limited.
In a section in which the K value is less than 1.05, total energy
(total Q) has a constant value, and in a section in which the K
value is more than 1.05, total Q tends to be increased.
In a section in which the K value is less than 1.05, feeding
calorie Qc is larger than required calorie Qr, and thus, required
process energy is maintained at a constant value.
In a section in which the K value is more than 1.05, feeding
calorie Qc is smaller than required calorie Qr, and thus, required
process energy is increased.
In a section in which the K value is less than 1.05, uncondensed
calorie (QNC) occurs, and thus, it is seen that vapor in the upper
portion of the first distillation column is not completely
condensed and process operation becomes unstable.
In a section in which the K value is more than 1.05, LP required
calorie (QLP) occurs, so that utility required for the second
distillation column is increased and total Q is increased.
When the K value is increased, the composition of the product tends
to be increased, and when the K value is 0.95 or more, the standard
is appropriate.
As described above, preferred exemplary embodiments of the present
invention have been described, but the scope of the present
invention is not limited thereto, and the present invention has
been described in detail in specific parts, and it is obvious that
such specific technique is only a preferred embodiment to a person
skilled in the art, without limiting the scope of the present
invention thereby. Thus, the substantial scope of the present
invention will be defined by the appended claims and their
equivalents.
* * * * *